Telephone-line



(No Model.)

T. B. DOOLITTLE.

TELEPHONE LINE.

No. 297,683. Patented Apr. 29, 1884.

UNITED STATES PATENT @rrrcir.

THOMAS B. DOOLITTLE, OF BRIDGEBORT, CONNECTICUT.

TELEPHONE-LINE.

SPECIFICATION forming part of Letters Patent No, 297,683, dated April29, 188%.

Application filed February 21, 1883. (No model.) v

T001, whom it may cancer/1,:

Be it known that I, THos. B. DOOLITILE, of Bridgeport, in the county ofFail-field and State of Connecticut, have invented certain Improvementsin Telephone-Lines, of which the following is a specification.

My invention relates to an improvement in the art of telephony, whichrelates more particularly to the character of the supports to which theline-wires are attached.

The object of my invention is the augmentation of volume and clearncssof the articulation of the reproduced words.

It is well known,and has been for along time; that,although telegraphy,to be successful, demands a highly-insulated conductor for the currentsemployed, such is not the case with telephony. This is referred to in alecture delivered by A. Graham Bell, October 81, 1877, before theSociety of Telegraph Engineers, London, in which he describes the use ofthe railroad -track for conversational purposes. In practice it hasoften been found advantageous to employ uninsulated telephone-lines, andthe results have been invariably favorable during the continuance of dryweather. The reason of this is not positively known, and there are amongelectrical experts conflicting theories upon the subject; but it hasbeen demonstrated by experience that although in dry weather the resultsare as indicated favor able, in wet weather the escape frequentlybecomes so great as to render telephonic communication difficult, and tocompletely prevent the, electric signaling between stations which isnecessary to call attention prior to the transmission of a message.

The design of myinvention, is specifically, to obviate this drawback touninsulated lines, and to enable such lines to work equally well in wetor damp as in dry weather; and to this end it consists in a devicewhereby the amount of current escaping may be limited and maintained aconstant quantity, irrespective of variation in the hydroscopiccondition of the atmosphere. At each point of support of thetelephone-wire, instead of mounting the said line-wire simply on anordinary pin on the one hand, or upon a glass or porcelain insulator onthe other, I construct a grooved supporting device of wood in the formof an insulator and supporting pin therefor combined, and I cover theparts of the same, which are, when in use, exposed to the atmosphere,with a water-proof paint or varnish, which is also a non-conductor, withthe exception of the groove where the line-wire absolutely rests.

In the drawings which illustrate my invention, Figure 1 shows a sectionof a telephone-line of four wires fitted with my improved device. Fig. 2shows an elevation of the insulator-shaped supporting-pin, and Fig.

3 is a sectional elevation of the same.

In Fig. 1 a series of line-wires, w,are shown, extending from one pole,P, to another, and resting on the painted wooden pins A, whichare-inserted in the cross-arms c.

In Fig. 2, e is the shank of the supportingpin A, and from the shoulderd to the apex of the said pin the surface thereof is made waterproof bythe application of a suitable paint or varnish. Between the lower part,f, and the uppper part, g, of the supportingpin is a groove, (4, whichis left unpainted. In this groove the wire is fastened in the usual way,and is thus in contact with the substance of the wooden pin, and throughit and the body of the cross-arm and of the pole to the earth, the pole,cross-arm, and pin composing the high resistance, which is necessary inall such earth-contacts. As shown in Fig. 3, the under surface of theoverhanging part f is made concave, the edge forming a petticoat,b,which aids the drip of any moisture and prevents it from continuingdown the surface of the pin. Vere it not for the waterproofing of thesur face of the support, the entire substance of the said support wouldin wet weather become permeated with moisture, thereby acquiring a highconductive power, and thus a large proportion of the working-currentwould be lost by escape through the pin and down the pole; but whenconstructed as I have described, the pin being covered with animpenetrable waterproof and insulating-coating, maintains its drycondition,and hence its electrical conducting-power remains constant andwhile a sufficient escape is maintained by means of the contact of theline-wire with the unpainted groove, and by means of the imperfect insu-IOO lating properties of the dry wood, that escape is not exceeded,andremains uniform, keeping the line in .an electrical condition similar tothat of the earth, whereby retardation is prevented. The leaving of thegroove (4 uncoated is of great importance where the paint or varnishused is also an insulator or non conductorofelectrieity; butif thewaterproofing material used be such as does not impair the conductivityof the support, the purposes of the invention will be as wellaccomplished if the groove be waterproofed as well as the other parts ofthe support.

I claim- 1. A telephone-linehaving a series of earthconnectionsofamaterial of low conductivitysuch as wood-said material having itssurface coated with water-proof material, substantially as described.

2. A telephone-line upheld by a series of supports, of wood or similarmaterial, of low conductivity, having their surface coated with waterproof material, substantially as" de scribed.

3. A support for telephone-wires, consisting:

of a wooden pin inserted in a pole or cross-arm, and made waterproof atall parts of its surface, except the point on which the eonductingavireabsolutely rests, substantially as described.

4. Asupport for telephone-1ines, consisting of a wooden pin and agrooved wire-holder at its upper part, the surface of the said pin beingpainted or varnished, as described, to prevent the substance of the pinfrom acquiring moisture, and the groove thereof beinglcft unpainted,whereby the normal escape is maintained constant, substantially asdescribed.

5. A support for telephone lines, havingits surface coated or coveredwith a waterproofing and insulating material, except where the wirerests, substantially as described.

In testimou y whereof I have signed my name to this specification, inthe presence of two subscribing witnesses, this 13th day of l cbruary,1883.

T. B. DOOLITTLE.

Witnesses:

J. H. Grrnnvnn, DANIEL DAVENPORT.

